United States patent application Ser. No. 525,416 filed Nov. 20, 1974 in the names of Victor Bernin, Robert Madland and Carl Knoll and entitled, "Magnetic Keyswitch" is a Continuation of United States patent application Ser. No. 474,571 filed May 30, 1974 and now abandoned, which in turn was a Continuation of United States patent application Ser. No. 388,510 filed Aug. 15, 1973 and also now abandoned. These applications show a magnetic switch which utilizes a single saturable magnetic core that is mounted in a unitary insulating support assembly which also supports the drive line and sense line wires of the switch.
A unitary support assembly is a highly desirable feature for many applications since the depressible actuator and keystem of the switch can easily be separated from the magnetic core and its associated sense and drive line wires so that components of the switch, such as a return spring, can be replaced without complete dismantling of the switch, in particular, without unsoldering the drive and sense line wires from a printed circuit board to which they are connected.
The unitary support assembly of the aforementioned applications, however, was of a one-piece plastic construction in which the drive and sense line wires were molded into place in the support while the core was held in place by a pair of cantilevershaped flexible braces. While this construction provided the advantages noted above, it was difficult to manufacture since the drive and sense line wires had to be threaded through the core and the core had to be positioned in place at the molding station. In addition, the presence of the sense and drive line wires in the mold cause molding problems including mold breakages due to misalignment of the component parts.
The present invention is directed to a unitary support assembly which retains the desired advantages of the prior mentioned switch of the Bernin et al applications, but which is manufactured in a more economical and efficient manner. This is achieved by constructing the support assembly so that it has the same generally outer configuration as the support assembly of the Bernin et al applications, but so that it is formed of two identical molded plastic members which may be snapped together to form a support assembly wherein the core and drive and sense line wires may be inserted into the assembly away from the molded station.
The support assembly of the present invention has several desirable features not found in prior magnetic keyswitches of this type. First, the core is allowed to float in its restraining receptacle that is supported in the support assembly when the two plastic members are snapped together. This eliminates any undue pressure on the core which could adversely affect its performance. Next, the molded plastic members are formed so that the drive and sense line wires may be placed in the support assembly on either side of the core despite the fact that one of them preferably has a bend in it to provide greater separation between the terminal ends of the wires. In addition, the support formed by the two molded plastic members has a projecting guide means thereon that prevents the magnets on the plunger from rubbing against the core so as to prevent another possible source of keyswitch failure.